#!/usr/bin/env python3

import os
import requests
import enum
from pathlib import Path
from urllib import parse as urlparser
import sys
import subprocess
import configparser
import zlib
import json

handler = None

if sys.platform == "win32":
    import msvcrt


def stdout_set_binary():
    if sys.platform == "win32":
        msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)


class VerbosityType(enum.IntEnum):
    ERROR = 0
    INFO = 1
    DEBUG = 2


def cout(line: str):
    sys.stdout.write(line)
    sys.stdout.flush()


def cerr(line: str):
    sys.stderr.write(line)
    sys.stderr.flush()


def cin() -> str:
    return sys.stdin.readline().strip()


def writeln(msg: str = None):
    if msg is None:
        cout('\n')
    else:
        cout('{}\n'.format(msg))


def writerr(msg: str = None):
    if msg is None:
        cerr('\n')
    else:
        cerr('{}\n'.format(msg))


class GitRemoteIpfs:
    def __init__(self, rname: str, rpath: str):
        # CONSTANTS
        self.EMPTY_TREE_HASH = '4b825dc642cb6eb9a060e54bf8d69288fbee4904'
        # DIRECTORIES
        self.project_dir = Path(
            subprocess.check_output(['git', 'rev-parse', '--show-toplevel']).decode('utf-8').rstrip())
        self.git_dir = Path(self.project_dir / Path('.git'))
        Path(self.git_dir / Path('ipfs')).mkdir(parents=True, exist_ok=True)
        # CONFIG
        self.configuration = configparser.ConfigParser()
        self.configuration.optionxform = str  # Workaround for case-sensitive use case
        self.configuration_file = Path(self.git_dir / Path('ipfs') / Path('config')).absolute()
        if not self.configuration_file.is_file():
            writerr('''
Initial configuration not found!

    IPFS remote processor cannot find the configuration file.
    It is usually placed under your repository's root directory
    by path .git/ipfs/config
    
    Likely it happened because the IPFS remote repository was not
    initialized properly. To initialize it, select the proper
    IPFS ID (CID if you have cloned the repository from immutable
    source on IPFS network or gateway, or IPNS name to turn on
    data republishing under peer-signed unique link name), and
    call 'git ipfs install' command:
    
        git ipfs install
    
    to initialize your repository for working with IPFS remote.  
''')
            sys.exit(1)
        self.configuration.read(self.configuration_file)
        self.ipfs_config = self.configuration['IPFS']
        self.ipfs_api_base = self.ipfs_config.get('URL', 'http://127.0.0.1')
        self.ipfs_api_port = self.ipfs_config.getint('Port', 5001)
        self.ipfs_version_prefix = self.ipfs_config.get('VersionPrefix', 'api/v0')
        self.ipfs_api_url = urlparser.urljoin(self.ipfs_api_base + ':' + str(self.ipfs_api_port),
                                              urlparser.quote(self.ipfs_version_prefix))
        self.ipfs_request_timeout = self.ipfs_config.getfloat('Timeout', 30.0)
        self.unpin_old = self.ipfs_config.getboolean('UnpinOld', False)
        self.republish_ipns = self.ipfs_config.getboolean('Republish', False)
        self.ipns_ttl = self.ipfs_config.get('IPNSTTLString', '2h')
        self.cid_version = self.ipfs_config.getint('CIDVersion', 0)
        self.ipfs_chunker = self.ipfs_config.get('IPFSChunker', 'size-262144')
        self.ipfs_api_username = self.ipfs_config.get('UserName', None)
        self.ipfs_api_token = self.ipfs_config.get('UserPassword', None)
        self.ipfs_api_auth = None
        if self.ipfs_api_username is not None and self.ipfs_api_token is not None:
            self.ipfs_api_auth = (self.ipfs_api_username, self.ipfs_api_token)
        # API ACCESS
        try:
            api_response = requests.post(self.ipfs_command('version'), auth=self.ipfs_api_auth)
        except requests.exceptions.ConnectionError:
            writerr(
                'Cannot access IPFS API at {}! Please check if you have a running node at the specified URL!'.format(
                    self.ipfs_api_url))
            sys.exit(1)
        if api_response.status_code == 200:
            response_content = api_response.json()
            writerr('Found IPFS API node version {} at {}'.format(
                response_content['Version'] + '~' + response_content['Commit'],
                self.ipfs_api_url))
        else:
            writerr(
                'Cannot access IPFS API at {}: HTTP response {}, abort'.format(self.ipfs_api_url,
                                                                               api_response.status_code))
            sys.exit(1)
        # URIs
        self.url = self.ipfs_api_url
        self.remote_name = rname
        self.remote_path = rpath
        # IPFS REPOSITORY
        self.ipfs_path = self.remote_path.split('://')
        if len(self.ipfs_path) < 2:
            writerr('Unable to parse remote URL for {}: {}'.format(self.remote_name, self.remote_path))
            sys.exit(1)
        self.timeout = self.ipfs_request_timeout
        writerr('Checking remote URL {} for valid baremetal repository'.format(self.remote_path))
        req_param = {
            'arg': '/ipns/' + self.ipfs_path[1],
            'headers': False,
            'resolve-type': True,
            'size': False,
            'stream': False
        }
        self.accessible_repo = False
        self.ipns_repo = False
        self.empty_repo = False
        # IPFS FILESYSTEM
        try:
            api_response = requests.post(self.ipfs_command('ls'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
            if api_response.status_code == 200:
                self.accessible_repo = True
                writerr('Found valid IPNS entry')
                self.ipns_repo = True
        except requests.exceptions.ReadTimeout:
            writerr('Valid IPNS repository not found at {}'.format(self.remote_path))
            self.accessible_repo = False
        if not self.ipns_repo:
            req_param['arg'] = self.ipfs_path[1]
            try:
                api_response = requests.post(self.ipfs_command('ls'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
                if api_response.status_code == 200:
                    writerr('Found valid immutable IPFS entry')
                    self.accessible_repo = True
            except requests.exceptions.ReadTimeout:
                writerr('Valid immutable IPFS entry not found at {}'.format(self.remote_path))
                self.accessible_repo = False
        self.ipfs_path = req_param['arg']
        # GIT
        self.references = {}
        # MISC
        self.verbosity = VerbosityType.DEBUG

    def ipfs_command(self, command: str):
        return self.ipfs_api_url + '/' + command

    def run(self):
        while True:
            cmd = cin()
            if cmd == 'capabilities':
                writeln('option')
                writeln('list')
                writeln('push')
                writeln('fetch')
                writeln()
            elif cmd.startswith('option'):
                self.option(cmd)
            elif cmd.startswith('list'):
                self.listing(cmd)
            elif cmd.startswith('push'):
                self.push(cmd)
            elif cmd.startswith('fetch'):
                self.fetch(cmd)
            elif cmd == '':
                break
            else:
                cerr('Unsupported operation: {}\n'.format(cmd))
                sys.exit(1)

    def option(self, opt: str):
        if opt.startswith('option verbosity'):
            self.verbosity = VerbosityType(int(opt[len("option verbosity "):]))
            writeln('ok')
        else:
            writeln('unsupported')

    def listing(self, opt: str):
        prepare_push = 'for-push' in opt
        references = self.git_references(prepare_push)
        for hash, refname in references:
            writeln('{} {}'.format(hash, refname))
        if not prepare_push:
            head = self.read_symbolic_reference('HEAD')
            if head is not None:
                writeln('@{} HEAD'.format(head))
            else:
                if self.verbosity >= VerbosityType.INFO:
                    writerr('No default branch on remote {}'.format(self.remote_name))
        writeln()

    def push(self, opt: str):
        remote_head = None
        marked_deletion = []
        push_objects = {}
        push_references = {}
        push_size = 0
        forced = False
        while True:
            source_ref, destination_ref = opt.split(" ")[1].split(":")
            if len(source_ref) == 0:
                if self.verbosity == VerbosityType.DEBUG:
                    writerr('Marking {} for deletion'.format(destination_ref))
                head = self.read_symbolic_reference('HEAD')
                if head is not None and head == destination_ref:
                    writerr('Reference {} refused to delete current branch {}'.format(destination_ref, head))
                else:
                    marked_deletion.append(destination_ref)
                    writeln('ok {}'.format(destination_ref))
            else:
                if self.verbosity == VerbosityType.DEBUG:
                    writerr('Reference to push: {}:{}'.format(source_ref, destination_ref))
                if source_ref.startswith('+'):
                    forced = True
                    source_ref = source_ref[1:]
                referenced_objects = [i.split()[0] for i in
                                      subprocess.check_output(['git', 'rev-list', '--objects', source_ref]).decode(
                                          'utf-8').strip().split('\n')]
                writerr('Compressing objects...')
                # Writing objects
                for obj in referenced_objects:
                    obj_typestring = subprocess.check_output(['git', 'cat-file', '-t', obj]).decode('utf-8').strip()
                    obj_size = subprocess.check_output(['git', 'cat-file', '-s', obj]).decode('utf-8').strip()
                    obj_data = obj_typestring.encode('utf-8') + b' ' + obj_size.encode('utf-8') + b'\0'
                    if obj_typestring is not None:
                        obj_data += subprocess.check_output(['git', 'cat-file', obj_typestring, obj],
                                                            stderr=subprocess.DEVNULL)
                    else:
                        obj_data += subprocess.check_output(['git', 'cat-file', '-p', obj], stderr=subprocess.DEVNULL)
                    obj_encoded = zlib.compress(obj_data)
                    del obj_data
                    obj_path = obj[:2]
                    obj_name = obj[2:]
                    obj_posixpath = Path.as_posix(Path('objects') / Path(obj_path) / Path(obj_name))
                    if self.verbosity == VerbosityType.DEBUG:
                        writerr('[{:^10}] {}: compressed to {:.2%} ({} vs {} bytes)'.format(obj_typestring, obj, float(
                            len(obj_encoded)) / float(obj_size), obj_size, len(obj_encoded)))
                    push_objects[obj_posixpath] = obj_encoded
                    push_size += len(obj_encoded)
                if self.verbosity == VerbosityType.DEBUG:
                    writerr('Referencing {}'.format(source_ref))
                ref_hash = subprocess.check_output(['git', 'rev-parse', source_ref]).decode('utf-8').strip()
                if not forced:
                    found_hash = None
                    for entry in self.references:
                        if entry[1] == destination_ref:
                            found_hash = entry[0]
                            break
                    if found_hash is not None:
                        if subprocess.call(['git', 'cat-file', '-e', found_hash], stdout=subprocess.DEVNULL,
                                           stderr=subprocess.DEVNULL) != 0:
                            writeln('error {} fetch first'.format(destination_ref))
                        else:
                            if subprocess.call(['git', 'merge-base', '--is-ancestor', found_hash, ref_hash],
                                               stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) != 0:
                                writeln('error {} non-fast forward'.format(destination_ref))
                    else:
                        push_references[destination_ref] = ref_hash
                        writeln('ok {}'.format(destination_ref))
                else:
                    push_references[destination_ref] = ref_hash
                    writeln('ok {}'.format(destination_ref))
                if self.empty_repo:
                    if remote_head is None or subprocess.check_output(['git', 'rev-parse', source_ref]).decode(
                            'utf-8').strip() == subprocess.check_output(['git', 'rev-parse', 'HEAD']).decode(
                        'utf-8').strip():
                        remote_head = subprocess.check_output(['git', 'rev-parse', source_ref]).decode(
                            'utf-8').strip()
            opt = cin()
            if len(opt) == 0:
                if self.empty_repo:
                    if self.verbosity == VerbosityType.DEBUG:
                        writerr('Setting up default branch on the remote HEAD...')
                    self.empty_repo = False
                    if remote_head is not None:
                        push_references['HEAD'] = 'ref: ' + destination_ref
                    else:
                        writerr('Push to empty repository without specifying a default branch')
                        push_references['HEAD'] = subprocess.check_output(['git', 'rev-parse', source_ref]).decode(
                            'utf-8').strip()
                else:
                    push_references['HEAD'] = 'ref: ' + destination_ref
                break
        if self.verbosity == VerbosityType.DEBUG:
            writerr('''\n{:*^30}

Objects:
=======
{}
=====
Total: {}, {} bytes

References:
==========
{}
=====
Total: {}

Marked for deletion:
===================
{}
=====
Total: {}
'''.format(' SUMMARY ',
           '\n'.join('{}\t{}'.format(k, len(push_objects[k])) for k in push_objects.keys()),
           len(push_objects),
           push_size,
           '\n'.join('{:<30} {:<50}'.format(k[:30], push_references[k]) for k in push_references.keys()),
           len(push_references),
           '\n'.join('{}. {}'.format(*k) for k in enumerate(marked_deletion)),
           len(marked_deletion)))
        writerr('Preparing IPFS data for upload')
        req_param = {
            'quiet': False,
            'quieter': False,
            'silent': False,
            'progress': False,
            'trickle': False,
            'only-hash': False,
            'wrap-with-directory': True,
            'chunker': self.ipfs_chunker,
            'raw-leaves': True,
            'cid-version': str(self.cid_version),
            'pin': True
        }
        files = {}
        for o in push_objects.keys():
            files[o] = push_objects[o]
        for o in push_references.keys():
            files[o] = push_references[o]
        if subprocess.call(['git', 'update-server-info'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) != 0:
            writerr('Cannot update repository internal placement information. Abort')
            sys.exit(1)
        objects_location_info = (Path(self.git_dir) / Path('objects/info/packs')).open('rb').read()
        references_location_info = (Path(self.git_dir) / Path('info/refs')).open('rb').read()
        files['objects/info/packs'] = objects_location_info
        files['info/refs'] = references_location_info
        writerr('Uploading data...')
        wrapper_dir_hash = None
        try:
            api_response = requests.post(self.ipfs_command('add'), params=req_param, files=files, auth=self.ipfs_api_auth, timeout=self.timeout)
            if api_response.status_code == 200:
                wrapper_dir_hash = \
                json.JSONDecoder().decode(api_response.content.decode('utf-8').rstrip().split('\n')[-1])['Hash']
                writerr(
                    '\nNew immutable IPFS CID for repository (for dumb cloning etc.):\n\t{}'.format(wrapper_dir_hash))
        except requests.exceptions.ReadTimeout:
            writerr('Unable to upload data to IPFS node! Please check API accessibility!')
            sys.exit(1)
        if self.ipns_repo:
            req_param = {
                'arg': self.ipfs_path,
                'recursive': True,
                'nocache': False,
                'dht-timeout': str(self.timeout) + 's',
                'stream': False
            }
            api_response = requests.post(self.ipfs_command('name/resolve'), params=req_param, auth=self.ipfs_api_auth)
            old_cid = None
            if api_response.status_code == 200:
                old_cid = api_response.json()['Path'].split('/')[-1]
                writerr('Old commit CID:\n\t{}\n'.format(old_cid))
                if self.unpin_old:
                    req_param = {
                        'arg': self.ipfs_path,
                        'recursive': True
                    }
                    api_response = requests.post(self.ipfs_command('pin/rm'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
                    writerr('''{:*^30}
{}
'''.format(' UNPINNED ', '\n'.join('{}'.format(k) for k in api_response.json()['Pins'])))
            if self.republish_ipns and wrapper_dir_hash is not None:
                ipns_key = self.ipfs_path.split('/')[-1]
                writerr('Attempting to republish IPNS name:\n\t{}'.format(ipns_key))
                req_param = {
                    'arg': wrapper_dir_hash,
                    'resolve': True,
                    'lifetime': self.ipns_ttl,
                    'allow-offline': True,
                    'key': ipns_key,
                    'quieter': False,
                    'ipns-base': 'base36'
                }
                api_response = requests.post(self.ipfs_command('name/publish'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
                if api_response.status_code == 200:
                    writerr(
                        'IPNS name republished, you may access the pushed commits via IPNS\nNo remote URL update required')
                else:
                    writerr(
                        'ATTENTION! Unable to update IPNS name!\n\tPlease use new CID listed above to access the pushed commits!')
        else:
            if wrapper_dir_hash is not None:
                writerr('Updating remote URL to: {}'.format(wrapper_dir_hash))
                if subprocess.call(['git', 'remote', 'set-url', self.remote_name, 'ipfs://' + wrapper_dir_hash]) != 0:
                    writerr('Unable to set remote CID! Please check the repository!')
                    sys.exit(1)
        writeln()

    def fetch(self, opt: str):
        while True:
            name, obj_hash, val = opt.split(' ')
            if self.verbosity == VerbosityType.DEBUG:
                writerr('Fetching object {} [{}] recursively'.format(val, obj_hash))
            download_queue = [obj_hash]
            while len(download_queue) > 0:
                # Examination of the download link
                obj = download_queue.pop()
                if subprocess.call(['git', 'cat-file', '-e', obj]) == 0:
                    if obj == self.EMPTY_TREE_HASH:
                        subprocess.Popen(['git', 'hash-object', '-w', '--stdin', '-t', 'tree'], stdin=subprocess.PIPE,
                                         stdout=subprocess.PIPE,
                                         stderr=subprocess.DEVNULL).communicate(b'')
                else:
                    obj_path = obj[:2]
                    obj_name = obj[2:]
                    obj_posixpath = Path.as_posix(Path('objects') / Path(obj_path) / Path(obj_name))
                    if self.verbosity == VerbosityType.DEBUG:
                        writerr('Downloading {}'.format(obj_posixpath))
                    req_param = {
                        'arg': self.ipfs_path + '/' + obj_posixpath,
                        'offset': 0,
                        'progress': False
                    }
                    obj_data = None
                    api_response = requests.post(self.ipfs_command('cat'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
                    if api_response.status_code == 200:
                        obj_data = zlib.decompress(api_response.content)
                    if obj_data is not None:
                        obj_header, obj_content = obj_data.split(b'\0', 1)
                        obj_typestring = obj_header.split()[0].decode('utf-8')
                        downloaded_hash = \
                        subprocess.Popen(['git', 'hash-object', '-w', '--stdin', '-t', obj_typestring],
                                         stdin=subprocess.PIPE,
                                         stdout=subprocess.PIPE,
                                         stderr=subprocess.DEVNULL).communicate(obj_content)[0].decode(
                            "utf-8").strip()
                        if downloaded_hash != obj:
                            writerr('Hash mismatch for object {}, downloaded data have hash {}'.format(obj,
                                                                                                       downloaded_hash))
                            sys.exit(1)
                # Examination of the local object
                obj_typestring = subprocess.check_output(['git', 'cat-file', '-t', obj]).decode('utf-8').strip()
                if obj_typestring == 'blob':
                    continue
                obj_data = None
                if obj_typestring is None or obj_typestring == 'tree':
                    obj_data = subprocess.check_output(['git', 'cat-file', '-p', obj],
                                                       stderr=subprocess.DEVNULL).decode('utf-8').strip()
                else:
                    obj_data = subprocess.check_output(['git', 'cat-file', obj_typestring, obj],
                                                       stderr=subprocess.DEVNULL).decode('utf-8').strip()
                if obj_typestring == 'tag':
                    if self.verbosity == VerbosityType.DEBUG:
                        writerr('Traversing tag {}'.format(obj))
                    download_queue += [obj_data.split('\n', maxsplit=1)[0].split()[1]]
                elif obj_typestring == 'commit':
                    if self.verbosity == VerbosityType.DEBUG:
                        writerr('Traversing commit {}'.format(obj))
                    lines = obj_data.split('\n')
                    tree = lines[0].split()[1]
                    objects = [tree]
                    for line in lines[1:]:
                        if line.startswith('parent '):
                            objects.append(line.split()[1])
                        else:
                            break
                    download_queue += objects
                elif obj_typestring == 'tree':
                    if obj_data is None:
                        continue
                    lines = obj_data.split('\n')
                    # Filtering submodule hashes
                    download_queue += [line.split()[2] for line in lines if not line.startswith("160000 commit ")]
                else:
                    writerr('Unexpected Git object type \'{}\' obtained for {}'.format(obj_typestring, obj))
                    sys.exit(1)
            opt = cin()
            if len(opt) == 0:
                break
        writeln()

    def read_symbolic_reference(self, ipfs_prefix: str):
        req_param = {
            'arg': self.ipfs_path + '/' + ipfs_prefix,
            'headers': False,
            'resolve-type': True,
            'size': True,
            'stream': False
        }
        try:
            api_response = requests.post(self.ipfs_command('ls'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
            if api_response.status_code != 200:
                if self.verbosity == VerbosityType.DEBUG:
                    writerr('Cannot find symbolic reference /{} on the opened IPFS remote'.format(ipfs_prefix))
                return None
        except requests.exceptions.ReadTimeout:
            if self.verbosity == VerbosityType.DEBUG:
                writerr('Cannot retrieve symbolic reference /{} from the IPFS remote'.format(ipfs_prefix))
            return None
        if self.verbosity == VerbosityType.DEBUG:
            writerr('Fetching symbolic reference /{}'.format(ipfs_prefix))
        req_param = {
            'arg': self.ipfs_path + '/' + ipfs_prefix,
            'offset': 0,
            'progress': False
        }
        api_response = requests.post(self.ipfs_command('cat'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
        return api_response.content.decode('utf-8').split(': ')[1].rstrip()

    def reference_names(self, ipfs_prefix):
        result = []
        req_param = {
            'arg': self.ipfs_path + '/' + ipfs_prefix,
            'headers': False,
            'resolve-type': True,
            'size': True,
            'stream': False
        }
        if self.verbosity == VerbosityType.DEBUG:
            writerr('Exploring IPFS directory ipfs:/{}'.format(req_param['arg']))
        api_response = requests.post(self.ipfs_command('ls'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
        ipfs_list = None
        if api_response.status_code == 200:
            ipfs_list = api_response.json()
        else:
            return []
        for entry in ipfs_list['Objects'][0]['Links']:
            if entry['Type'] == 1 and entry['Size'] == 0:
                result += self.reference_names(ipfs_prefix + '/' + entry['Name'])
            elif entry['Type'] == 2:
                result.append(ipfs_prefix + '/' + entry['Name'])
            else:
                if self.verbosity >= VerbosityType.INFO:
                    writerr(
                        'Possibly empty IPFS object {}:{} found on the repository'.format(entry['Name'], entry['Hash']))
        return result

    def git_references(self, prepare_push: bool):
        writerr('Running stat on remote references')
        result = []
        if not self.accessible_repo and not prepare_push:
            writerr('Error: cannot stat references from empty repo!')
            return []
        req_param = {
            'arg': self.ipfs_path + '/refs',
            'headers': False,
            'resolve-type': True,
            'size': True,
            'stream': False
        }
        api_response = requests.post(self.ipfs_command('ls'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
        entries = []
        if api_response.status_code == 200:
            entries = self.reference_names('refs')
            for entry in entries:
                req_param = {
                    'arg': self.ipfs_path + '/' + entry,
                    'offset': 0,
                    'progress': False
                }
                api_response = requests.post(self.ipfs_command('cat'), params=req_param, timeout=self.timeout, auth=self.ipfs_api_auth)
                result.append((api_response.content.decode('utf-8').strip(), entry))
        else:
            writerr('It seems you have cloned an empty repository')
            self.empty_repo = True
            return []
        for entry in result:
            self.references[entry[1]] = entry[0]
        return result


stdout_set_binary()
writerr('Git IPFS remote client')

handler = GitRemoteIpfs(sys.argv[1], sys.argv[2])
handler.run()
